The new Sony Reader Daily Edition will be available in December for $399, Sony announced today at an event in New York. It operates on AT&T's 3G network, offering the ability to purchase and download e-books from anywhere in the U.S. -- a feature that's new to Sony, but one that Amazon's Kindle has offered since the beginning.

The Daily Edition includes a 7-inch touchscreen in a widescreen format, and uses the same "e-ink" screen that Sony's other readers (and Amazon's Kindles) use.

Unlike the Kindle, it will not have a rudimentary Web browser, Sony's Steve Haber told us today. But it does have access to more than one million free, public-domain books, via a partnership with Google, and access to free books from public libraries. (We don't know much more about it. Sony did not offer any hands-on time, and did not give any software demos.)

How will it do? Touchscreen with wireless is a strong feature set that Amazon hasn't yet matched, so Sony has an advantage there. But there's time left for Amazon to unveil a similar device before the holiday season. (We've asked Amazon for comment, but don't expect to hear anything about their plans.)

Either way, the e-reader market is still in its early stages.

While this year's crop -- now including three Readers from Sony, and two Kindles from Amazon -- may find a million or more buyers, this is a lot like the first few years of the MP3 player market. There are more features to sort out before mainstream adoption will happen: Color touchscreens, perhaps; e-book formats and DRM "openness"; lower pricing, etc. While Sony and Amazon spar over minor advancements, neither is offering a must-have device today.